In known manner, surgeons prefer to use techniques that are not very invasive, making use of narrow access paths in order to treat vascular diseases. Such techniques make it possible to limit recourse to open surgery and they are therefore less burdensome for the patient. For this purpose, use is often made of a catheter or an endoscope that possesses at its end a steerable elongate body for the purpose of facilitating insertion and advance of the elongate body inside the human body.
The structure of the elongate body includes at least one actuator member enabling its end to be curved so as to enable it to negotiate bends and move into non-rectilinear portions of the human body, or indeed in order to view and to treat portions of the body that are not located on the main axis of the elongate body.
Various types of actuator member have been proposed, some of which use shape memory alloy wires (referred to below as SMAWs).
The SMAWs extend along the elongate body, with their ends being anchored thereto. The SMAWs are associated with means for heating them, e.g. by the Joule effect, thereby causing them to contract in order to cause the elongate body to bend. For this purpose, electrical power supply wires are connected to the SMAWs.
Nevertheless, such structures are difficult to fabricate. The SMAW must both be fastened at its ends to the longitudinal body and must also be connected to the power supply wire.
Various ways of securing SMAWs to the body have been proposed, such as adhesive or indeed lasers, but they are not very satisfactory since they do not make it possible to guarantee both that the wire is accurately positioned on the longitudinal body and that it is properly held over time, in particular given the large variations of temperature in the SMAW, and the high traction forces to which the SMAW is subjected.
It is important to emphasize that the positioning of the wire is particularly important when the longitudinal body carries a plurality of SMAWs, since it is necessary to prevent any contact between these wires in order to avoid short circuits.
Finally, it should also be observed that the extra thickness due to the SMAWs and to the means for connecting the SMAWs to the body must be minimized so that the assembly presents the compactness needed to enable the structure to pass along ducts of small diameters.